A conventionally known light deflector includes a polygon mirror made of plastic, and a motor including a rotor configured to support the polygon mirror. The rotor includes a base portion and a protruding portion protruding from the base portion. The polygon mirror has a through-opening at a center portion thereof, and the protruding portion of the rotor is inserted into the through-hole and the base portion of the rotor comes into contact with a bottom surface of the polygon mirror, so that the polygon mirror is attached to the rotor.
However, in this conventionally known light deflector, the surface of the base portion around the protruding portion entirely contacts the bottom surface of the polygon mirror, so that heat generated by the motor is easily transferred to the bottom surface of the polygon mirror. Therefore, the heat from the motor may be transferred to the reflecting surfaces of the polygon mirror through the bottom surface, and the reflecting surfaces may undergo a deformation due to thermal expansion.
In view of the above, it would be desirable to provide a light deflector which can suppress deformation of the reflecting surfaces of the polygon mirror due to thermal expansion of the reflecting surfaces.